What could time crystals be useful for? Time crystals have been theorized only a few years ago and confirmed recently. The articles reporting it don't talk about what they could be used for. Of course, every branch of physics can help us understand the world better, but have there been any proposals for a practical application of time crystals?
There are, and were, events especially in nuclear physics when a practical application of something was thought of before it was first proven or synthesized. What about the so called "time crystals"? What can they be used for where regular superconductors are not enough?
 A: This is a review article on the status of the research by summer of 2017. I copy the conclusions:

In the present article we have reviewed current state of
  the art of investigations of time crystals originally pro-
  posed by Wilczek (Wilczek, 2012), i.e. the phenomena
  that are related to self-organization of quantum many-
  body systems in time. This kind of self-organization is a
  truly quantum effect and should be distinguished from
  classical self-organization phenomena where non-linear
  oscillators synchronize their motion if a coupling between
  them is sufficiently strong . The formation of time crystals is quite
  analogous to the formation of space crystals. 

....

While the original time crystal proposition turned out
  to be impossible for realization, Wilczek’s vision triggered a new research field and became an inspiration to
  other scientists. 

Goes on to describe recent proposals and ends with:

We believe
  that a current strong activity in the field of time crystals
  will reveal novel phenomena that are difficult to discover
  in condensed matter systems or simply overlooked so far.
  Bearing in mind that a time degree of freedom adds an additional dimension, more possibilities for new discoveries are opened.

Nowhere in this review is a list for "practical  applications'.
In general searches one finds vague proposals that time crystals will be useful for quantum computing:

While Yao is hard put to imagine a use for a time crystal, other proposed phases of non-equilibrium matter theoretically hold promise as nearly perfect memories and may be useful in quantum computers.

So, imo it is still at the research level, experimental and theoretical, and it is too soon to gauge the possible applications. After all when Maxwell came up with his equations which predicted electromagnetic waves, ~1860s Herz measured them in 1887, almost thirty years later, and the first practical application with communications happened in in the 1890's . At the time of the electromagnetic wave proposal wireless communications were not even dreamed about.
With our accelerated times  ( 5 years between Wilczek's proposal and experiments, and the  many researchers working away) applications should not be far away.
A: Time crystals could be very useful in quantum computing and possibly in fusion, for similar reasons. Essentially time crystals provide a more stable quantum environment then your run-of-the-mill particle beam.
Because time crystals have some self-persistence of their state, even without external input temporarily, they also have extra resilience to all the randomness of heat entropy and external vibrations. This makes them ideal for some designs of qubit RAM.
It should also be theoretically possible to create a time and spatial lattice at high pressures and temperatures, but it is unknown to me what level of technology that's going to require. The resonance stress on the materials would be rather high I think.
Surely other uses exist. One other quantum computing use would be a timer.

REFERENCE
Equilibration and order in quantum Floquet matter 

R. Moessner & S. L. Sondhi

Observation of a discrete time crystal

J. Zhang, P. W. Hess, A. Kyprianidis, P. Becker, A. Lee, J. Smith, G. Pagano, I.-D. Potirniche, A. C. Potter, A. Vishwanath, N. Y. Yao & C. Monroe

Discrete time crystal in a finite chain of Rydberg atoms without disorder

Chu-hui Fan, D. Rossini, Han-Xiao Zhang, Jin-Hui Wu, M. Artoni, and G. C. La Rocca Phys. Rev. A 101, 013417

Observation of a prethermal discrete time crystal, regarding exploring metastable states in nonequilibrium thermodynamics

A. Kyprianidis, F. Machado, W. Morong, P. Becker, K. S. Collins, D. V. Else, L. Feng, P. W. Hess, C. Nayak, G. Pagano, N. Y. Yao, and C. Monroe

